{"doi":"10.3389/fvets.2025.1603375","title":"Case Report: Adverse reaction to butorphanol in a Collie homozygous for the ABCB1-1∆ (MDR1) mutation","abstract":"Certain dog breeds, particularly herding breeds like Collies, are predisposed to drug sensitivity due to the ABCB1-1∆ (previously known as MDR1 ) mutation, which disrupts P-glycoprotein (P-gp) function. This mutation impairs drug efflux at the blood–brain barrier, leading to increased susceptibility to neurotoxic effects. While adverse reactions to P-gp substrate drugs such as macrocyclic lactones and chemotherapeutics are well documented, opioid sensitivity remains poorly understood. This case report documents a Collie that developed severe neurotoxicity, including profound sedation, ataxia, hypersalivation, and seizures, following a single 0.2 mg/kg dose of butorphanol. Symptoms persisted despite supportive care, requiring continuous naloxone administration for approximately 40 h before significant improvement. Neurotoxicological effects may have been exacerbated by metoclopramide and maropitant, known P-gp substrates. This case underscores the need for further research into opioid pharmacokinetics in ABCB1-1∆ mutant dogs and highlights the importance of genetic screening in veterinary practice. To enhance patient safety, integration of automated alerts within electronic medical record systems is recommended to flag high-risk drugs for at-risk breeds, providing real-time warnings, dosing adjustments, and monitoring guidance. These measures could reduce adverse drug reactions and improve clinical outcomes in genetically susceptible dogs.","journal":"Frontiers in Veterinary Science","year":2025,"id":567179,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9578,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":863583,"name":"Heather N. Allen","orcid":"0000-0003-0771-1959","position":1,"is_corresponding":false},{"id":1471639,"name":"April Hardison","orcid":null,"position":2,"is_corresponding":false},{"id":1471640,"name":"Erin Miscioscia","orcid":null,"position":3,"is_corresponding":false},{"id":254857,"name":"Rajesh Khanna","orcid":"0000-0002-9066-2969","position":4,"is_corresponding":false},{"id":1471343,"name":"Elizabeth A. Maxwell","orcid":"0000-0002-8201-040X","position":5,"is_corresponding":false},{"id":325506,"name":"Tyler S. Nelson","orcid":"0000-0002-6675-4820","position":0,"is_corresponding":true}],"reference_count":25,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-19T02:56:44.340853Z","pmid":"40510379","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}